Jar



Oct. 17, 1961 Filed Sept. 27, 1956 B. P. NUTTER ETAL JAR rfn/ U 2Sheets-Sheet 1 ,cla-2 www :xfa

2 sheets-sheet 2 B. P. NUTTER ET AL JAR Oct. 17, 1961 Filed sept. 27,195e United States Patent() 3,004,616 JAR 'Ihis invention relates towell jars and, more specifically, to well jars of the hydraulic typeyfor use with oil well testing equipment.

In carrying on oil well testing procedures, various testing tools andone or more packers are connected to a pipe string and lowered into awell bore. The packers are set to seal off the well bore and standardtesting procedures are followed, using the testing tools. At the end ofthe test, the packers are released and the pipe string is removed fromthe well. Sometimes, however, the packer or tools below it may becomestuck in the well. To 'overcome this problem, a jar is often connectedin the pipe string above the upper packer where it may be operated tofree the stuck object so that the pipe string may be removed. If a jaris not placed inthe pipe string, there is the danger that the pipestring may be broken in attempting to remove it by a manipulation of thepipe string alone. Thus, a pipe string may often be Ifreed by repeatedimpacts of a jar, although stuck too tight to be freed by straighttensioning.

From the foregoing, it would appear that it would always be advisable toinsert a jar in the pipe string in the eventuality that testingequipment becomes stuck in the well bore, but in practical usage this isnot always done. The jar is but one of many tools to be connected attheend of the pipe string, and the total length of the tools is animportant practical consideration to be weighed in determining whatelements are to be fused. Hence, the utilization of many existing jarsis restricted because of their over-all length.

Therefore, it is an object of this invention to provide a new andimproved jar having a minimum overall length and, hence, `a greaterutility in well testing operations.

It is a further object of this invention to provide a new and improvedhydraulic jar utilizing iixed packing retainers for the hydraulic fluidchambers and having rotation prevention splines arranged to require noextension of the overall length.

It is a further object of this invention to provide a new and improvedhydraulic jar of economical and rugged construction adapted to bereadily maintained.

In accordance with the present invention, a well jar is provided whichincludes a mandrel and an annular housing together defining a uidchamber through which the mandrel extends. The housing has a grooved andan ungrooved bore portion of like diameter dening the outer wall of thechamber. A valve member carried by the mandrel moves from within theungrooved position to within thev grooved portion providing first for arestricted flow of iiuid, then for a rapid ow as the jar is extended. Ananvil is also carried by the mandrel and has longitudinally extendingsplines thereabout which are retained in the grooved portion to locksaid mandrel and housing against relative rotation. `An' impact face onthe mandrel strikes an impact face on the housing to terminate extensionof the jar and to impart a iarringblow to an object connected by Vthejar to the lower end of a drill string.

Other objects Vand advantages will become apparent in the followingdetailed description.

In lthe accompanying drawings, lforming a part of this application, andin which like numerals are used to designate like parts throughout thesame,

FIG. l is a sectional elevational view of a jar embodying the invention;

FIGS. 2 and 3 are sectional elevational views of the upper and lowerparts, respectively, of the jar of FIG. l on an enlarged scale, showingthe jar in collapsed position;

FIG. 4 is a partial sectional elevational view similar to FIGS. 2 and 3,showing the jar in extended position;

FIG. 5 is a cross-sectional view of the jar taken on line 5-5 of FIG. 2;and

FIG. 6 is a cross sectional view of the jar taken on line 6-6 of FIG. 4.v

In the drawings, there is shown for the purpose of illustrating apreferred embodiment of the invention, a jar which comprises an annularhousing member v11 having aniupper section 12, a middlesection 13, and ahammer sub 14, each being threadedly connected to the adjacent section.The Aupper housing section 12 is provided Ywith internal threads 16adapted to receive the lower end of a pipe string 17.

A mandrel 18, having an upper wash mandrel section 19, an intermediatesection 21, and a lower section 22, is internally and concentricallyreceived within the housing member 11 yfor limited longitudinal movementas a unit with respect to the housing member. The bottom end of themandrel 18 is provided with external threads 23 adapted to be connectedto conventional testing equipment 24. A central bore `25 provides a uidpassage lengthwise through mandrel 18.

The housing section 13 has upper and lower portions 26 and 27 of unequallength but with `equal internal diameters, these portions forming, withthe mandrel 18, a hydraulic fluid chamber 28. The chamber 28 is sealedat the top by a packing member 29 iixed by means of an annular externalilange 31 to the housing member 11 by the screw connection of housingsections 12 and 13.

An O-ring 32 seals against fluid flow from the chamber 28 past the outersurf-ace of packing member 29, and O- rings 33 and 34 prevent Huid flowbetween the mandrel 18 and the packing member 29. The lower end ofchamber 28 is sealed by means of 0rings '36, 37 and 38 which preventtluid ow between the hammer sub. 114 of housing member 11 and mandrel18. The mandrel 18 has'the same external diameter at the upper sealingmember 29 and at lower sealing rings 36, 37 and 38, and thus the chambervolume is maintained constant regardless of the relative longitudinalpositions of the mandrel and the housing member. A plug 39 allows thechamber 28 to be lled with a suitable hydraulic Huid. Y v

Surrounding the intermediate mandrel section 21 is an annular valvemember 41 having an external diameter slightly less than the internaldiameter of the lrelatively short upper portion 26 of the middle housingsection 13 to allow a restricted vlow of fluid between thevalve member41 and the portion 26. The valve member 41, as seen in FIGS. 2 and `6,has an internal diameter substantially greater than the outerdiameter ofthe corresponding portion of mandrel section 21 and is centered forsliding movement along the mandrel section by cireumferentially spacedlongitudinal splines 42 formed on said mandrel section, such splineshaving cylindrical outer surfacesv slidably ttted Within valve member41. An outwardly extending annular valve seat 43 is formed on themandrel section 21 to limit the upward movement of valve member 41 andto shut olf lluid llow through grooves 45 formed in eircumferentiallyspaced relation between the splines 42 when the valve member 41 isforced against the valve seat 43. An annular valve stop 44 surrounds themandrel section 21 below the valve member 41 and limits downwardmovement of the valve member to a travel sutiicient to open the valve.The internal diameter of the valve stop member 44 corre- Y n a spends tothe internaldiameter of the valve member 41, and lateral bores 46 formedthrough the valve stop member allow iluid communication from the chamber28 tothe grooves 45 between the valve member 41 and mandrel section 21when the valve memberrests against the valve stop member 44. Y

The mandrel section 22 is radially enlarged at its upper end to form Vananvil 46a having an annular downwardly facing impact face 47.Longitudinal splines 48 are formed on the external surface of anvil46a,`extend ing short of the impact face 47, and mating 4with grooves 49formed longitudinally of the inner surface ofJthe relatively long lowerportion 27 ofthe section 13. These splines and grooves prevent relativerotation'between the mandrel 18 and housing member 11, while permittinglimited relative longitudinal movement therebetween. As will be seen inFIG. 5, the housing portion 27 has a greater number of grooves 49 thanthe anvil V46a has splines and thus there is relatively free fluidcommunica-V tion'from one side of anvil 46a to the other in chamber 28through the unoccupied grooves 49.

The hammer sub 14 of housing member 11 has an upwardly directed impactface 52 adapted to contact the anvil impact face 47 when the jar 10 ispulled into itsl extended position. n

The jar is assembled as in FIG. 1 with the chamber 4 allow for thelengthof the iluid chamber 28 and the extendible length of the mandrel 18 withrespect to the housing member 11.

The provision that the mandrel splines 48 terminate Short of the anvilimpact face'47 insures that no impact will be delivered to the splines48 upon the sudden extension of the jar, and thus eliminates thepossibility that the relatively thin splines will'be sheared from theanvil upon impact. I

It is to be understood that the form of the invention, herewith shownand described, is to be taken as a preferredY embodiment ofthe same, andthat various changes in the shape, size and arrangement of parts may bere# 28 being filled with hydraulic uid, and is connected to the lowerend of a pipe string 17 and to the upper end of a packer element 24 of aconventional tester. If at the end of a test the packer, or any oftheother testing elements, is stuck in the well bore, the stuck object maybe jarred loose in the following manner. A steady stress is applied tothe upper end of the well string, thus urging the housing member 11upwardly while the mandrelV 18, being connected to the stuck object,remains stationary, As Ithehousing portion `26 moves upwardly withrespect to valve member 41, the valve member is urged against the valveseat 43 and the uid in the lower portion of chamber 28 is subjected topressure.v Since the fluid is essentially non-compressible, no relativemovement results between thelhousing member 11 and mandrel 18 except-that provided by the transfer of fluid from the lower to the upper sideof the valve member through the re# stricted passage between the valvemember and housing portion 26. A- certain length of time is requiredVfor the valve member 41 to move out of the housing portion 26, andduring this timethe upward pull on the pipel string imparts a stretch tothe pipe string. At the instant the valve member 41 clears the housingportion 26, a relatively free passage is providedfor the compressedfluid vin the lower section ofnchamber 28 `around the valve member 41and the stretched pipe contracts upwardly, causing the housing member 11to suddenly rise with respect to the mandrel to the. extended positionshown in FIG. 4. The hammersub-impact face 52 strikes the anvil pactface 47, thus imparting a violent blow to the mandrel 18 and thestuckrobject to whichitis connected.

If this one lblow. is insuicient todislodgethe stuck object, the housingmember 11 is again lowered. The valve member 41 moves downwardly againstthe valve stop member, thus providing a relatively unobstructed flowpath to the fluid in the upper end of chamberl 28 to the lower end ofthat chamber.. With the jar 10 again in a collapsed position, anotherupward blow may beimparted to the stuck object as discussed previously.Success'ive blows may be generated until the stuck object becomesdislodged.

It will be noted that the'overall length of the jar 1t) is kept to aminimum by 'using a xed packing member 29 instead of a floating packingretainer, the latter Arequiring an additional length of housing in whichto float, an'd by the disposition ofl'the mandrel'splines 48 and housingmember grooves 49.c'o1`npletely within the lower portion of the fluidAcharr'iber 28. By this arrangement, the overall length of the jar 10need be only enough to sorted to, without departing from the spirit ofthe invention, or the scope of the attached claims.

l. A well jar comprising an annular housing member and a cylindricalmandrel concentrically carried therein, said housing member and saidmandrel being intertted for limited longitudinal movement relative toeach other between a contracted position andan extended position, saidhousing member and said mandrel providing opposite ends for said jaradapted for connection in a pipe string above an object which maybecomestuck in a well bore, annular seal means` of like diameter spacedlongitudinally apart for effecting a sliding seal between saidvhousingmember and mandrel to denean annular closed fluid-iilled chambertherebetween with said mandrel extending completely through said closedchamber, saidrhousing member having grooved and ungrooved portions ofequal internaldiameter forming the outer wall of said chamber, anenlarged portion of said mandrel intermediate the ends of said chamberhaving a valve seat thereon, a valve memberrcarried by said mandrel andmovable between a closed and an open position with respect to said seatby Huid pressure as said mandrel is extended and contracted,respectively, said valve member cooperating with the ungrooved portionof said outer chamber wall to restrict iluid flow. past said enlarged.portion in its closed position Yand to enhance -uid flow therepast inits open position, and an annular anvil carried by said mandrel`slidably within said grooved portion of said outer chamber wall andclosed to uid flow therethrough, said grooved portion of said outerchamber wall providing unrestricted fluid flow around said anvil andaround said enlarged portionwhen said jar is proximate `to its extendedposition, said anvil and said housing meinber Ahaving confronting impactfaces adapted to contact when said mandrel and housing member move tosaid extended position, said anvil having at least one spline engaged insaid grooved portion of said outer chamber wall to prevent rotationbetween said mandrel and said housing member. A

2. A well jar comprising an annular housing member and amandrelconcentrically carried therein, said housing member and saidmandrel being interitted for limited longitudinal movement relative toeach other between a contracted positionhand an extended position, saidhousing member and saidmandrelproviding opposite `ends for. said jaradapted for connection in a pipe string above an object which may becomestuck in a well bore, seal means of like diameterspaced longitudinallyapart for effecting a sliding seal between said housing member andlmandrel to define an annular closed uidchamber therebetween with saidmandrel extending completely through said closed chamber, ,said housingmember having grooved and ungrooved portions ofequal internal diameterforming the outer wall-of the chamber, an en*- larged portion of saidmandrel intermediate the ends of said chamber providing a valve seat, avalve member movable ybetween a closed andan open position with respectto said seat by fluid pressure `as said mandrel is.

Y lextended and contracted, said valve member cooperating its closedposition and to enhance fluid flow therepast in its open position, saidgroove portion of said outer charm ber walll providing unrestrictedfluid flow around said enlarged portion and valve member when said jaris proximate to its extended position, and an anvil carried by saidmandrel and disposed within said grooved portion, said anvil and saidhousing member having confronting impact faces adapted to contact whensaid mandrel and housing member move to said extended position, saidanvil having at least one spline for engaging said grooved portion toprevent rotation between said mandrel and said housing member, each suchanvil spline terminating short of said anvil impact face and beingretained in said grooved portion. t

3. A well jar comprising an annular housing member and a sectionaltubular, mandrel concentrically carried therein, said housingmember andsaid mandrel being interfitted 4for limited longitudinal movementrelative to each other between a contracted position andan extendedposition, said housing member and said mandrel providing opposite endsfor said jar adapted for connection in a pipe string above an objectwhich may become stuck in a well bore, seal means of like diameterspaced longitudinally apart for effecting a sliding seal between saidhousing member and mandrel to define an annular closed fluid-filledchamber therebetween with said mandrel extending completely through saidclosed chamber, said housing member having grooved and ungroovedportions of equal internal diameter forming the outer wall of saidchamber, an enlarged portion of one section of said mandrel intermediatethe ends of said chamber having a valve seat thereon, a valve membercarried by said mandrel and movable between a closed and an openposition with respect to said seat by fluid pressure as said mandrel isextended and contracted, respectively, said valve member cooperatingwith the ungrooved portion of said outer chamber wall to restrict fluidflow past said enlarged portion in its closed position and to enhancefluid flow therepast in its open position, and an annular anvilintegrally carried by a second section of said mandrel slidably withinsaid grooved portion of said outer chamber wall and closed to fluid flowtherethrough, said `grooved portion of said outer chamber'wall providingunrestricted fluid flow around said anvil and around said enlargedportion when said jar is proximate to its extended position, said anviland said housing member having confronting impact faces adapted tocontact when said mandrel and housing member move to said extendedposition, said anvil having at least one spline engaged in said groovedportion of said outer chamber wall to prevent rotation between saidmandrel and said housing member, said ungrooved portion of said housingmember being substantially shorter than said grooved portion, said anvilthreadedly receiving an end of said one mandrel section to connect saidsecond section therewith, and said enlarged portion and said valvemember being completely received within said ungrooved portion when saidjar is fully contracted.

4. A well jar comprising an annular housing member and a mandrelconcentrically carried therein, said housing member and said mandrelbeing interfitted for limited longitudinal movement relative to eachother between a contracted position and an extended position, saidhousing member and said mandrel providing opposite ends for said jaradapted for connection in a pipe string above an object which may becomestuck in a well bore, seal means spaced longitudinally apart foreffecting a sliding seal between said housing member and mandrel todefine an annular closed fluid chamber therebetween with said mandrelextending completely through said closed cham'ber, said seal meanshaving a fixed longitudinal spacing and the same effective diameter,said housing member having grooved and ungrooved portions of equalinternal diameter forming the outer wall of the chamber, an enlargedportion of said mandrel intermediate the ends of said chamber providinga valve seat of annular configuration carried by said mandrel, a valvemember of annular configuration slidable a limited longitudinal distancealong said mandrel between a 'closed and an open position with respectto said seat by fluid pressure as said mandrel is-extended andcontracted, said valve seat sealing with said valve member when saidmandrel and housing member are being extended, said valve membercooperating with the ungrooved portion of said outer uid chamber wall torestrict fluid flow past said enlarged portion in its closed positionand to enhance fluid flow therepast in its open position, said groovedportion of said outer chamber wall providing unrestricted fluid flowaround said enlarged portion and valve member when said jar is proximateto its extended position, and an anvil carried by said mandrel anddisposed within said grooved portion, said anvil and said housing memberhaving confronting impact faces adapted to contact when said mandrel andhousing member move to said extended position, said anvil having atleast one spline for engaging said grooved portion to prevent rotationbetween said mandrel and said housing member.

5. A well jar comprising an annular housing member and a mandrelconcentrically carried therein, said housing member and said mandrelbeing inteltted for limited longitudinal movement relative to each otherbetween a contracted position and an extended position, said housingmember and said mandrel providing opposite ends for said jar adapted forconnection in a pipe string above an object which may become stuck in awell bore, seal means spaced longitudinally apart for effecting asliding seal between said housing member and mandrel to define anannular closed fluid chamber therebetween with said mandrel extendingcompletely through said closed chamber, said seal means having a fixedlongitudinal spacing and the same effective diameter, said housingmember having grooved and ungrooved portions of equal internal diameterforming the outer wall of the chamber, an enlarged portion of saidmandrel intermediate the end of said chamber providing a valve seat ofannular configuration carried by said mandrel, a valve member of annularconfiguration slidable a limited longitudinal distance along saidmandrel between a closed and an open position with respect to said seatby fluid pressure as said mandrel is extended and contracted, said valveseat sealing with said valve member when said mandrel and housing memberare being extended, said valve member cooperating with the ungroovedportion of said outer fluid chamber wall to restrict fluid flow pastsaid enlarged portion in its closed position and to enhance fluid flowtherepast in its open position, said grooved portion of said outerchamber wall providing unrestricted fluid flow around said enlargedportion and said Valve member when said jar is proximate to its extendedposition, and an anvil carried by said mandrel and disposed within saidgrooved portion, said anvil and said housing member having confrontingimpact faces adapted to contact when said mandrel and housing membermove to said extended position, said anvil having at least one splinefor engaging said grooved portion to prevent rotation between saidmandrel and said housing member, an annular apertured stop memberdisposed around said mandrel intermed-iate said val-ve member and saidanvil, said mandrel being relieved to provide a passage extendingbeneath said valve member and terminating interiorly of said stop memberfor the flow of fluid therethrough when said jar is being contracted.

6. A Well jar comprising an annular housing member and a mandrelconcentrically carried therein, said housing member and said mandrelbeing interfitted for limited longitudinal movement relative to eachother between a contracted posit-ion and an extended position, meansadapted to connect one end of the housing member -to a pipe string,means adapted to connect the opposite end of the mandrel to an objectwhich may become -stuc'kIin a well bore, sealmeans of like diameterspaced longitudinally vapart for effecting a sliding seal between saidjhousing member and mandrel to deline an annular closed fluid chambertherebetween with `said mandrel extending completely through said closedchamber, said housing member having adjacent grooved and ungroovedportions extending longitudinally of the chamber, an annular valvemember surrounding said mandrel and adapted to be received in theungrooved portion of said housing member when the well jar is in itscontracted position, the outer diameter of said valve member'beingslightly smaller than the diameter of said ungrooved portion to'permitrestricted iluid flow between the valve member and said ungroovedportion, said valvevr member having an inner bore cooperating with theunderlying portion of said mandrel to dene a passage extendinglengthwise beneath said valve member, a valve seat of annularconiiguration on an Yenlarged portion of said mandrel intermediate theends of said chamber, said valve member being adapted to seat on saidvalve seat, an annular Valve stop member surrounding said mandrel andadapted to allow said valve to move a limited distance from said valvemem,- ber seat passage means in said valve stop member allowing uidcommunication from the passage provided between said mandrel and said=valve member-to the outer surface of said valve stop member, said valvemembersbeing adapted to tbe completely received 4in the grooved portionof said housing member when said jar is in extended position, an anvilhaving an impact face carried, by said mandreljand disposed within saidgrooved housing portion, said anvil serving to position said valve stopmember with respect to said mandrel, said housing member having animpact face defining the lower end of said chamber and adapted tocontact the impact face of said anvil when said mandrel and housingmember move to said extended position, and a plurality of splines formedlongitudinally of said anvil and received in said grooved housingportion lto prevent relative rotation between said mandrel andY saidhousing member, said grooved portion affording a longitudinal passagefor the passage of fluid around said anvil and said valve member.

7. A well jar comprising an annular housing member and a mandrelconcentrically carried therein, said housing member and said mandrelbeing interfitted for lim- Y 8 ited longitudinal movement relativev toeach other between a contracted position and an extended position, saidhousing Amember and said mandrel providing opposite ends for said jaradapted for connection in a well string above'l an object which maybecome stuck in a well bore, seal means of like diameter spacedlongitudinally apart for effecting a sliding seal between said housingmember and mandrel to define an annular closed fluid-filled chambertherebetween with said mandrel extending completely through said closedchamber, said housing member having grooved and ungrooved portions ofequal internal diameter forming the outer wall of said chamber, anenlarged portionV of said mandrel intermediate the ends of said chamberhaving a valve seat thereon, a valve member carried by said mandrel andmovable between a closedV and an open position with respect to said seatby fluid pressurel as said mandrel is extended Vand contracted, saidvalve member cooperating with Ithe ungrooved portion of said outerchamber wall to restrict uid ilow past said enlarged portion in itsclosed position and to enhance fluid ow therepast in its open position,and an annular anvil carried by said mandrel slidably within saidgrooved portion of said outer chamber wall, said grooved portion of saidouter chamber wall providingunrestricted iluid iow around said anvil andaround said enlarged portion when said jar is proximate to its extendedposition, said anvil and `said housing member having confronting impactfaces adapted to contact when said mandrel and housing member move tosaidextended position, said mandrel carrying at least onersplineengaged-in said grooved portion of said outer chamber -wall along alength of said wall which overlaps substantially with Ithe lengththereof traversed by lsaid enlarged portion in movement of said mandrelfrom its contracted to itsextended position, thereby to prevent rotationbetween said mandrel and said housing member.

References Cited in the file .of this patent Osmun Dec. v 1, 1957

